A crane lifted the large piece of sculpture and placed it within the empty pediment of the Cathedral Church of St. Paul, high above Tremont Street, on a recent sunny morning. A four-man crew fixed the piece in place, attaching it to a bright blue backdrop that will be lit at night when the new look for a very old church is formally celebrated on Wednesday.

In traveling 60 feet skyward, the piece, made of hand-formed aluminum and weighing 650 pounds, completed a journey that, in a sense, began nearly 200 years ago.

Until now, St. Paul’s, with its stately sandstone columns and recessed granite facade, has not had a very interesting exterior, said The Very Rev. John “Jep” Streit, dean of the Episcopal church, as he watched the installation from the sidewalk.

“People think it’s a bank or a courthouse,” said Streit, who wore a Red Sox baseball cap with his khaki suit and clerical collar. “We wanted something that would say, ‘What’s going on in there? Let’s go see.’ We wanted to invite people inside.”

The sculpture, titled “Ship of Pearl,” resembles a crosscut view of a chambered nautilus, its shell spinning outward. Designed by noted artist Donald Lipski, it borrows its title from the opening line of a poem by Oliver Wendell Holmes celebrating the nautilus as a symbol of constant change and spiritual growth.

Built in 1819-20, St. Paul’s, which faces the Park Street T station on Boston Common, was once the largest structure in its downtown Boston neighborhood. Above its columned front, done in Greek Revival style, was supposed to be a relief of St. Paul preaching before King Agrippa.

That artistic flourish was never added, however. Funds ran out, and the triangular space atop the church portico, measuring 75 feet wide and 16 feet high at its apex, was left unfilled. It would remain so for the next 194 years.

The new pediment sculpture is part of a $4 million church renovation project, which will add glass panels to the front of the building as well as skylights, an elevator, and upgrades to its heating and cooling systems.

The pediment art is eye-catching, to say the least. Lipski is a New York City-based artist known for his large-scale public works. He won the St. Paul’s commission over 130 other artists in a six-month-long competition that ended early last year.

Lipski was beaming as he oversaw the final installation. Four days before, the sculpture had arrived by truck from Denver, where it had been manufactured under the supervision of Juno Works, a design firm specializing in custom metal fabrication.

Last-minute issues with getting the necessary permits — the piece arrived not long after the Boston Marathon bombings, when local agencies remained on high alert — were resolved in time to proceed on schedule. Scaffolding was removed Friday, giving congregants and passersby their first unobstructed view of the new sculpture.

Lipski said his biggest challenge was choosing an appropriate symbol or image. He wanted one spiritual in nature yet not narrowly or specifically Christian, he recalled, in keeping with the church’s all-inclusive mission.

In 1912, St. Paul’s was designated a cathedral and became the seat of the Episcopal Diocese of Massachusetts. Today, it also serves large groups of Muslims — more than 400 of whom use St. Paul’s as their spiritual home, praying there weekly — and Chinese Episcopal congregants, Lipski noted. In addition, the church has a 30-year tradition of ministering to Boston’s homeless population with food and shelter.

Dina Rudick/Globe Staff

The sculpture, called “Ship of Pearl,” was created by Donald Lipski.

“It really is a special building and special place, which made me approach the project with a respect for its complexity,” said Lipski, whose work is collected in the Metropolitan Museum of Art, the Corcoran Gallery in Washington, and the Art Institute of Chicago. He has also designed about two dozen public works spread across the United States, from Manhattan’s Grand Central Terminal and Central Park to the Miami International Airport and Washington D.C. Convention Center.

While doing research on Boston and St. Paul’s, Lipski came across the Holmes poem, “The Chambered Nautilus” — a happy surprise, he recalled, since the poem (“Build thee more stately mansions, O my soul/As the swift seasons roll!”) was composed in the early years of the church’s existence.

Nevertheless, Lipski worried about placing such a nontraditional image on a Greek Revival building and whether that might offend architectural purists. Fortunately for Lipski, his design passed muster with a jury that included congregants, representatives from local museums and art schools, and Streit himself, who shared the design with city officials.

“Donald’s was so clearly right, so obvious, it was everything I’d hoped for — religious and holy but not too narrowly so,” recalled Streit. Others were similarly enthusiastic, he said.

Like the nautilus, Christianity is constantly growing and changing, he continued. A more conventional work might have pleased traditionalists, and quieted objections from those preferring a representation of Jesus Christ instead, not an abstract form drawn from nature.

Wendy Maeda/Globe staff

The sculpture, called “Ship of Pearl,” was created by Donald Lipski.

“I understand that,” said Streit. “But to me that doesn’t capture the provocative nature of Christ. Putting his image on a cathedral would be an old story, in some sense. This is a new story. ‘Come in and see,’ it says.”

One critic of the piece is Matthew Alderman, a project architect with the Concord-based firm Cram & Ferguson. Alderman feels “Ship of Pearl” represents a missed opportunity on the church’s part.

“It’s an interesting piece of art, certainly, and would make a marvelous front for a natural history museum,” said Alderman, who has seen renderings of the design but not the installation itself. “To me, though, it doesn’t really represent anything in an iconographic, Christian way.”

Streit takes such criticism in stride. St. Paul’s has never been a wealthy church, he noted, and spending $200,000 on an art commission might seem like a luxury. But art is supposed to be elevating, after all. And Lipski’s piece fulfills that mission.

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